Keep in mind that the 5870s/5830s are dual slot video cards unless you watercool or something similar. So for dual slot cards this mobo supports 4 max it looks like. You're better off saving money and buying an AMD system (cheaper mobo and cpu). I have an MSI board that has 5 pci-e slots but will support 4 dual slot cards.

You could do 6 cards by using PCI-E extenders. Just a warning though you run the risk of exploding the motherboard if you run 6 5870s, as the PCI-E bus still delivers power to cards despite having external power connectors. I don't know the exact numbers, the spec calls for 75W max, so say 40 * 6 = 240W running through the PCIE Bus.

Of note, a $200 motherboard that requires a $200+ CPU isn't necessarily that money saving. You can find cheap AMD AM3 boards with 5 PCI-slots (x1 works fine) for ~$120 with a $40 sempron that saves you > $250.

In fact you could get 2x $120 mobos + 2x $40 CPUs, have 10 slots for cards and still have spent less than you would have on LGA1366.

You could do 6 cards by using PCI-E extenders. Just a warning though you run the risk of exploding the motherboard if you run 6 5870s, as the PCI-E bus still delivers power to cards despite having external power connectors. I don't know the exact numbers, the spec calls for 75W max, so say 40 * 6 = 240W running through the PCIE Bus.

Of note, a $200 motherboard that requires a $200+ CPU isn't necessarily that money saving. You can find cheap AMD AM3 boards with 5 PCI-slots (x1 works fine) for ~$120 with a $40 sempron that saves you > $250.

In fact you could get 2x $120 mobos + 2x $40 CPUs, have 10 slots for cards and still have spent less than you would have on LGA1366.

what kind of AMD AM3 boards have 5 PCI-E slots which could install a graphic card?

I list some of the resources that you may be interested in while planning your mining rig in my Building "guide" including this.

Also, I think it isn't that difficult to find specification on the GD-70, take heed that,as darvil, I also assume you're not putting them in a case, and you probably have to solve the PSU problem (as I had to initially which I didn't and gave up) if you put so many GPU on on MOBO. (Max PSU prolly around 1500 W, you'll need more than that)

I tried running with 6 HD5870 on a single MB but I could only get 4 out of the 6 to work properly, XFX couldn't see any reason why but figured it was down to resource problems with the MB - I've since changed to use 3xHD5870 per MB.

I tried running with 6 HD5870 on a single MB but I could only get 4 out of the 6 to work properly, XFX couldn't see any reason why but figured it was down to resource problems with the MB - I've since changed to use 3xHD5870 per MB.